US 7438125 B2
A plunger mechanism comprises an adjustable bypass valve. Depending on well parameters, a user may desire to adjust the descent rate of a plunger in service. The present device allows the user to vary or adjust the bypass orifice to alter the flow of liquid through the plunger core.
1. A variable orifice bypass plunger comprising:
a cylindrical body having an upper end, a lower end, and an internal channel therethrough, said internal channel capable of passing a fluid from said upper end;
said lower end connectable to valve assembly comprising a push rod positionable in an open and a closed bypass mode;
said valve assembly further comprising a variably sized or adjustable inlet, said inlet in communication with said internal channel; and
wherein said valve assembly further comprises an outer body having an inlet hole and a rotatable control cylinder mounted therein, said rotatable control cylinder having a hole in a closure wall, wherein a rotation of said rotatable control cylinder adjusts said holes of said outer body and said rotatable control cylinder in relation to one another.
2. The plunger of
3. The plunger of
4. The plunger of
5. The plunger of
6. The plunger of
7. An internal bypass plunger comprising:
a plunger body having an internal conduit with an inlet at its bottom and an outlet at its top;
said plunger bottom comprising a push rod movable from an extended position which leaves said inlet open, to a retracted position which closes said inlet;
said plunger bottom further comprising a side opening and a rotatable cage mounted inside, said cage comprising ahole aligned with said side opening;
wherein a change in the alignment of said side opening and said cage hole varies said inlet; and
wherein said rotatable cage further comprises a releasable lock assembly to maintain a rotated position until a user changes it.
8. The plunger of
9. The plunger of
10. The plunger of
11. The plunger of
12. A variable bypass plunger comprising:
a plunger body having a fluid channel and an inlet thereto at its bottom;
a variable bypass assembly connectable to said bottom;
said variable bypass assembly comprising a rotatable casing with a side hole;
wherein an internal fixed cage comprises a side hole alignable with said casing side hole to provide a variable orifice in fluid communication with said bottom inlet; and
wherein a push rod is mountable in said variable bypass assembly to open and close said bottom inlet.
13. A variable orifice valve adapted to connect to an internal bypass plunger, said valve comprising:
an upper neck having a threaded connection for a plunger bottom;
said valve having a lower end with a clutch brake for a centrally mounted push rod;
said push rod having an upper valve head to seal an outlet of said upper neck in a retracted position, and open said outlet in an extended position;
said valve having an external housing with an inlet hole;
a rotatable cage mountable in said external housing; and
wherein a hole in said cage is moveable in relation to said external housing inlet hole to provide a variable orifice for said outlet.
14. The valve of
15. The valve of
16. The valve of
17. A variable orifice valve for an internal bypass plunger, the apparatus comprising:
a housing capable of providing a connection at its upper end to a lower end of a plunger;
said housing having a lower end comprising a clutch to support a push rod in a set position;
said push rod capable of opening and closing said upper end; and
a cage means mountable in said housing, said cage means capable of rotation to a desired position so as to align a cage hole with a housing hole, thereby providing a variable orifice to said upper end.
18. The apparatus of
19. The apparatus of
This application is a non-provisional application claiming the benefits of provisional application Ser. No. 60/563,711 filed Apr. 20, 2004.
The present apparatus relates to a plunger lift apparatus for the lifting of formation liquids in a hydrocarbon well. More specifically the plunger comprises a variable orifice in a bypass plunger apparatus that operates to allow a variation in plunger bypass capabilities as a function of well parameters.
A plunger lift is an apparatus that is used to increase the productivity of oil and gas wells. In the early stages of a well's life, liquid loading is usually not a problem. When rates are high, the well liquids are carried out of the well tubing by the high velocity gas. As a well declines, a critical velocity is reached below which the heavier liquids do not make it to the surface and start to fall back to the bottom exerting back pressure on the formation, thus loading up the well. A plunger system is a method of unloading gas in high ratio oil wells without interrupting production. In operation, the plunger travels to the bottom of the well where the loading fluid is picked up by the plunger and is brought to the surface removing all liquids in the tubing. The plunger also keeps the tubing free of paraffin, salt or scale build-up. A plunger lift system works by cycling a well open and closed. During the open time, a plunger interfaces between a liquid slug and gas. The gas below the plunger will push the plunger and liquid to the surface. This removal of the liquid from the tubing bore allows an additional volume of gas to flow from a producing well. A plunger lift requires sufficient gas presence within the well to be functional in driving the system. Oil wells making no gas are thus not plunger lift candidates.
As the flow rate and pressures decline in a well, lifting efficiency declines geometrically. Before long the well begins to “load up”. This is a condition whereby the gas being produced by the formation can no longer carry the liquid being produced to the surface. There are two reasons this occurs. First, as liquid comes in contact with the wall of the production string of tubing, friction occurs. The velocity of the liquid is slowed, and some of the liquid adheres to the tubing wall, creating a film of liquid on the tubing wall. This liquid does not reach the surface. Secondly, as the flow velocity continues to slow, the gas phase can no longer support liquid in either slug form or droplet form. This liquid along with the liquid film on the sides of the tubing begin to fall back to the bottom of the well. In a very aggravated situation, there will be liquid in the bottom of the well with only a small amount of gas being produced at the surface. The produced gas must bubble through the liquid at the bottom of the well and then flow to the surface. Because of the low velocity, very little liquid, if any, is carried to the surface by the gas. Thus, a plunger lift will act to remove the accumulated liquid.
A typical installation plunger lift system 100 can be seen in
Master valve 7 should be sized correctly for the tubing 9 and plunger 200. An incorrectly sized master valve 7 will not allow plunger 200 to pass through. Master valve 7 should incorporate a full bore opening equal to the tubing 9 size. An oversized valve will allows gas to bypass the plunger causing it to stall in the valve.
If the plunger is to be used in a well with relatively high formation pressures, care must be taken to balance tubing 9 size with the casing 8 size. The bottom of a well is typically equipped with a seating nipple/tubing stop 12. Spring standing valve/bottom hole bumper assembly 11 is located near the tubing bottom. The bumper spring is located above the standing valve and can be manufactured as an integral part of the standing valve or as a separate component of the plunger system. Fluid accumulating on top of plunger 200 may be carried to the well top by plunger 200.
Surface control equipment usually consists of motor valve(s) 14, sensors 6, pressure recorders 16, etc., and an electronic controller 15 which opens and closes the well at the surface. Well flow ‘F’ proceeds downstream when surface controller 15 opens well head flow valves. Controllers operate on time, or pressure, to open or close the surface valves based on operator-determined requirements for production. Modern electronic controllers incorporate features that are user friendly, easy to program, addressing the shortcomings of mechanical controllers and early electronic controllers. Additional features include: battery life extension through solar panel recharging, computer memory program retention in the event of battery failure and built-in lightning protection. For complex operating conditions, controllers can be purchased that have multiple valve capability to fully automate the production process.
Modern plungers are designed with various sidewall geometries (ref.
Recent practices toward slim-hole wells that utilize coiled tubing also lend themselves to plunger systems. Because of the small tubing diameters, a relatively small amount of liquid may cause a well to load-up, or a relatively small amount of paraffin may plug the tubing.
Plungers use the volume of gas stored in the casing and the formation during the shut-in time to push the liquid load and plunger to the surface when the motor valve opens the well to the sales line or to the atmosphere. To operate a plunger installation, only the pressure and gas volume in the tubing/casing annulus is usually considered as the source of energy for bringing the liquid load and plunger to the surface.
The major forces acting on the cross-sectional area of the bottom of the plunger are:
In certain high liquid wells, fluid build up hampers the plunger's decent during the return trip to the bumper spring at the well bottom. Thus, wells with a high fluid level tend to lessen well production by delaying the cycle time of the plunger system, specifically delaying the plunger return trip to the well bottom. Prior art designs have utilized by-pass valves within plungers. These by-pass valves permit the fluid to flow through the plunger during the return trip to the bumper spring at the well bottom. The by-pass valve provides a shut off feature when the plunger reaches the bottom. This open by-pass feature allows a faster plunger travel time down the hole in high liquid wells. Although by-pass valves are manufactured to allow fluid pass through, optimization of the by-pass opening size for the valve is difficult due to variations in well liquid loading. As well conditions change, different by-pass openings are required for optimization. The prior art solution tends the use of a variety of bypass plungers, each with a different size orifice opening. Thus, the optimization of prior art plunger lifts in a high liquid well is difficult with a fixed size orifice by-pass design. When the plunger falls slowly to the bottom of the well, it decreases well efficiency. Plunger drop travel time slows or limits well production. Well production increases are always critical.
What is needed is a plunger lift apparatus whose orifice size can be tuned to well conditions at the well itself and whose orifice size can be quickly changed at the well site as well liquid loading conditions change over time. The invention must function in a high liquid well, be one that can insure continuous efficiency during lift, drop back to the well bottom quickly and easily and assist in increasing well production by increasing lift cycle times. The apparatus of the present invention provides a solution to these issues.
One aspect of the present device is to provide a variable orifice by-pass plunger apparatus that can increase well production levels in a high liquid well.
Another aspect of the present device is to provide a by-pass plunger apparatus with a by-pass orifice that can be easily varied at the well itself to several different positions.
Another aspect of the present device is to provide a by-pass plunger that could efficiently force fall inside the tubing to the wellhole bottom with increased speed without impeding well production.
Another aspect of the present device is to allow for a by-pass valve to be shut once the plunger reaches the well bottom in order to provide for proper plunger return lift to the well top.
Yet another aspect of the present device is to allow for the plunger by-pass valve to be re-opened to its preset condition once the plunger reaches the well top.
Another aspect of the present device is to allow for various plunger sidewall geometries to be utilized.
Other aspects of this device will appear from the following description and appended claims, reference being made to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.
The present device comprises a plunger lift apparatus having a top second with an inner diameter allowing for liquid by-pass, and a bottom second comprising a variable by-pass valve to allow fluid to flow through the valve and up through the top section during the return trip to the bumper spring at the well bottom. The device typically comprises an inside top hollow orifice design (typically a standard American Petroleum Institute fishing neck).
The variable orifice by-pass plunger (VOBP) allows more than one orifice setting in the by-pass valve. Depending on the high liquid well parameters, the VOV can be set to optimize the VOBP return time to the well bottom, thus optimizing the production efficiency of the well.
The VOBP comprises a variable orifice valve (VOV) that has a variable orifice that can easily be set to more than one position. When released from an auto catcher, an orifice functions to allow liquid to pass through the plunger's lower valve section and up through the plunger's top second during its trip to the well bottom. The well control system will release the plunger to fall in the well when conditions are satisfied. Once at the well bottom, the lower valve section is designed to shut off the by-pass feature when striking the aforementioned bumper spring. Upon its trip to the well top, the aforementioned extracting rod within the lubricator will cause the device's valve section to re-open at its predetermined set condition.
The present device helps to assure an efficient lift in a high liquid well due to its design. The present device can also optimize well efficiency due to the fact that it has a field-adjustable orifice to allow it to quickly travel to the well bottom.
Before explaining the disclosed embodiment in detail, it is to be understood that the device is not limited in its application to the details of the particular arrangement shown, since the device is capable of other embodiments. Also, the terminology used herein is for the purpose of description and not of limitation.
Referring now to the drawings, the disclosed device provides a variable orifice by-pass plunger (VOBP) (see item 1000 of
The top second of a VOBP can be designed using various aforementioned plunger sidewall geometries (ref.
The bottom section, or variable orifice valve (VOV) 200, attaches to the VOBP top section. VOV 200 comprises a variable by-pass orifice to allow fluid to flow through the VOV and up through the top section during the plunger's trip to the bumper spring at the well bottom.
The disclosed device allows more than one orifice opening setting within VOV 200. That is, the variable orifice can easily be set to one or more positions. When released from the auto catcher, the orifice will function to allow liquid W (ref.
The disclosed device comprises an adjustable orifice to allow it to quickly travel to the well bottom. The orifice is thus field adjustable; it can be tuned at the well site depending on well parameters to optimize well cycle times. The higher the well pressure and/or liquid loading, the greater the orifice opening can be set. This results in the ability to optimize the bypass settings based on well conditions allowing the VOBP to fall to the bottom in an optimal manner. This avoids having to have a variety of different bypass valves, with various manufactured orifice openings, at the well site. The VOBP disclosed herein provides for the ability to field-adjust the bypass settings as well parameters change over time.
The VOBP may be employed as follows:
A drawing of an alternate embodiment (
Push rod brake clutch 21 comprises two half cylinders 23 each containing annular grooves to contain annular push rod brake clutch springs 23 and functioning to contain push rod 25 in either its open or closed positions. Bottom bumper striker end 34 can move push rod 25 into a closed position once VOBP hits the well bottom. Push rod closure end 37, outer closure ring 35 and rod slant surface 36 function to both close against VOBP top second at the well bottom and also to move to an open position when VOBP lifts to the well top. The striker rod within the lubricator (not shown) will strike against rod top end 37 to move push rod 25 into its open position thus allowing the VOBP to bypass fluids on its travel to the well bottom.
Variable control cylinder 26 comprises external adjustment hole 32 and four control cylinder orifices 31 which are spaced apart by about 90°. Variable control cylinder top source 46 shows nine preset position control half globe holes 33 located in groups of three, each group about 120° apart and each half globeholes within a group at about 20° apart. Control half globe holes 33 mate with balls 28 three at a time providing three preset through-orifice positions (full open, one-third open, two thirds open) in each of the four through orifices. The total opening, or through-orifice is a function of the position of the control cylinder orifices 31 with respect to the VOV body cylinder orifices 43.
When VOV 200 is assembled, control cylinder orifices 31 align with VOV main body cylinder orifices 43 such that the total through opening will be about 33%, 67%, or 100% depending on the positioning of variable control cylinder 26 in one of its three set positions. Adjustment slot 29 provides external tool 38 right movement direction TR or left movement direction TL functioning to set variable control cylinder 26 in one of its three positions via control cylinder adjustment control hole 32. VOV 200 is geometrically designed to have a fluid/gas dynamic type shape to allow it to quickly pass to the well bottom while allowing fluids to enter its orifice and pass through the top bored out section of the VOBP. Thus the VOBP will travel to the bottom with an efficient speed until it comes to rest on the bottom sitting or on a bumper spring, which will strike its push rod and close its bypass function.
The disclosed device allows for initial bypass tuning at the well site, allows future resets if necessary within one single plunger, and thus can assure well production optimization in high liquid gas wells.
It should be noted that although the hardware aspects of the VOV and VOBP of the present invention have been described with reference to the exemplary embodiment above, other alternate embodiments of the present invention could be easily employed by one skilled in the art to accomplish the variable bypass aspect of the present invention. For example, it will be understood that additions, deletions, and changes may be made to the variable orifice valve (VOV) with respect to design, adjustment mechanisms to set the orifice openings (such as ratchet type adjustments etc.), various orifice opening settings, orifice geometric design other than those described above, and various internal part designs contained therein.
Although the disclosed device has been described with reference to preferred embodiments, numerous modifications and variations can be made and still the result will come within the scope of the disclosure. No limitation with respect to the specific embodiments disclosed herein is intended or should be inferred.